I was actually thinking about this myself. The only problem is that skarmory and other walls are already annoying enough as is. Lets say for example, a player has out a skarmory. They get one layer of spikes as I switch in my magneton, another as I bring them down to sturdy, and a final layer after their salac berry activates and they outspeed me. This means that if they run a spin blocker, they'll have 3 layers of spikes up for most of the game, and there's nothing I can do about it. The balancing effect of entry hazards don't apply here either, as skarmory is immune to spikes and we have no access to stealth rocks. The real benefit this would offer is to walls, which are more than good enough already.